1. Genetics Since Mendel

2. Incomplete Dominance
Occurs when neither allele for a trait is dominant.
The phenotype produced is intermediate between the two homozygous parents
Ex. Coat color in purebred dogs

5. Multiple Alleles More than 2 alleles are multiple alleles
Traits controlled by multiple alleles produce more than 3 phenotypes.
In humans, blood type is controlled by 3 alleles (A,B,)- A & B are dominant. O is recessive

7. Polygenic Inheritance
A group of gene pairs acts together to produce a trait, which creates more variety in phenotypes.
Many human traits are controlled by polygenic inheritance, such as hair and eye color, height, body build, shape of eyes, lips and ears.

8. *Height is controlled by four
genes working together.
*Skin color is controlled by at
least three genes, each one
containing two different alleles.
Various combinations of
alleles produce the many skin
colors in humans

9. Mutations- genes that are altered or copied incorrectly
A mutation can be harmful, helpful, or have no effect
Chromosome disorders- caused by more or fewer chromosomes than normal
Down Syndrome- caused by 3 copies of chromosome 21

10. Significance of Mutations
Most are neutral
Eye color
Birth marks
Some are harmful
Sickle Cell Anemia
Down Syndrome
Some are beneficial
Sickle Cell Anemia immune to Malaria
Immunity to HIV

11. What Causes Mutations?
There are two ways in which DNA can become mutated:
Mutations can be inherited.
Parent to child
Mutations can be acquired.
Environmental damage
Mistakes when DNA is copied

12. Chromosome Mutations Down Syndrome
Chromosome 21 does not separate correctly.
They have 47 chromosomes in stead of 46.
Children with Down Syndrome develop slower, may have heart and stomach illnesses and vary greatly in their degree of inteligence.

13. Chromosome Mutations Cri-du-chat
Deletion of material on 5th chromosome
Characterized by the cat-like cry made by cri-du-chat babies
Varied levels of metal handicaps

15. Recessive Genetic Disorders
Both parents have a recessive allele responsible for the disorder and pass it on to their child.
Because parents are heterozygous, they don’t show symptoms
Cystic Fibrosis is a homozygous recessive disorder

16. Recessive Genetic Cont.
Genes that determine the sex of an organism are XX in females and XY in males. Males determine the sex of the offspring
Females produce eggs with x chromosomes only. Males produce sperm with either an x or a y chromosome.

18. Sex Linked Disorders
1. An allele inherited on an X or Y chromosome is a sex linked gene.
Colorblindness is a sex linked disorder caused by a recessive allele on the X chromosome. More common in males- females have to inherit it on both x’s.

19. Example of sex-linked trait
controlled by a recessive
allele: red-green color
blindness
Affects more
males than
females

20. What is a pedigree chart?
Pedigree charts show a record of the family of an individual
They can be used to study the transmission of a hereditary condition
They are particularly useful when there are large families and a good family record over several generations.
© 2007 Paul Billiet ODWS

21. Symbols used in pedigree charts
A marriage with five children, two daughters and three sons. The eldest son is affected by the condition.
Eldest child  Youngest child
Normal male
Affected male
Normal female
Affected female
Marriage
© 2007 Paul Billiet ODWS

22. Organising the pedigree chart
A pedigree chart of a family showing 20 individuals
© 2007 Paul Billiet ODWS

23. Organising the pedigree chart
Generations are identified by Roman numerals I II
III IV
© 2007 Paul Billiet ODWS

24. Organising the pedigree chart
Individuals in each generation are identified by Arabic numerals numbered from the left
Therefore the affected individuals are II3, IV2 and IV3 I II
III IV
© 2007 Paul Billiet ODWS

25. Advances in Genetics Genetic Engineering: Genes from one organism are
transferred into the DNA of
another organism
Used to produce medicine(insulin),
improve crops, and cure
genetic disorders

26. Bright face of genetically modified corn plant: pest-infected non-GM (left) and pest-free GM plant (right) planted side-by-side in a field trial. (photo: Dr. Yu Jialin, China Agricultural University)

27.                                                             
                                                      
French genetic researchers created Alba for artist Eduardo Kac. Thanks to genes borrowed from a jellyfish, the albino rabbit glows green when placed under special lighting. In regular light, Alba appears like any other furry white rabbit. But place her under a black light, and her eyes, whiskers and fur glow a otherworldly green.

29. Gene Therapy
A normal allele is placed into a virus, which delivers the normal allele when it infects its target cell.
May be used to control cystic fibrosis and other genetic disorders

30. Selective Breeding:
Breeding organisms with desired traits so that their offspring will have
those traits
Hybridization: Breeding two
genetically different individuals

32. SELECTIVE BREEDING
The Liger is the result of breeding a female Tiger to a male Lion.
The liger has both stripes and spots. The stripes are inherited from its tiger parent and the spots from the lion parent.
On their hind legs, ligers stand approximately 12 feet tall. At most, ligers may weigh up to 1,000 pounds.

33. The Cama is the result of breeding a Llama to a Camel
The Cama is the result of breeding a Llama to a Camel. Parents in background of picture.

34. The Zebroid is the result of breeding a female Horse and a male Zebra.
The Zedonk / Zonkey is the result of breeding a female Donkey and male Zebra.

35. The Mule is the result of breeding a female horse (mare) to a male donkey (jack). The mule is superior to the horse in strength, endurance, intelligence and disease resistance.

36. The Human Genome Project:
The main goal of the human
genome project is to identify
every gene in human DNA.
How can this help improve
modern medicine?